Saturday, January 28, 2012

When one thinks about Mammoths, they probably conjure up images of absolutely gigantic, hairy elephant-like mammals. The Pygmy Mammoths of the Channel Islands skew that image a bit- many were less than half the size of their mainland relatives!

At some point tens of thousands of years ago, a group of Columbian Mammoths made a six mile swim out to Santarosae, a "superisland" that existed when the ocean was 300 feet lower. Today only the very highest land points remain above water, and form four of California's Channel Islands.

Why did these 14ft tall, 20,000lb Mammoths swim so far? Perhaps they were allured by the smell of food! Mammoths, and modern Elephants, are excellent distance swimmers thanks to their trunks and buoyant bodies, so travelling a few miles for a buffet of fresh vegetation is a definite possibility!

Once on the island the Mammoths bred and the population grew. At the same time, the water levels rose, creating a larger gap between the island and mainland and trapping the Mammoths. As the number of animals rose, the amount of food fell. Having a smaller size (and thus requiring less sustenance) became the favored trait, and the Columbian Mammoths evolved and diverged into a new species.

Pygmy Mammoths were comparable in size to our modern Clydesdale Horses. They rarely stood larger than 7ft and weighed around 2,000lbs. A very far cry from the species they evolved from!

Fossils have been discovered on four of the Channel Islands, with the first specimens uncovered in the 1870s. A near-complete skeleton was unearthed in 1994.

Radiocarbon dating has shown that Mammoths were living on the islands for over 40,000 years. However, the species went extinct around 11,000 years ago, which was around the same time that many of the mainland megafauna species were also dying out.